Gelatin blasting explosive composition



Patented May 4, 1954 GELATIN BLASTING EXPLOSIVE COMPOSITION James Taylor, Ardrossan, Arthur J. Lowe, West Kilbride, and Edward G. Cooke, Ardrossan, Scotland, assignors to Imperial Chemical Industries Limited, a corporation of Great Britain No Drawing. Application June 7, 1950, Serial No. 166,766

Claims priority, application Great Britain July 29, 1949 11 Claims. 1

The present invention relates to new and improved gelatine blasting explosives. It is well known that the tendency is for the velocity of detonation and sensitivity characteristics of cartridges of gelatine explosive to diminish as the pressure under which they are used is increased.

The main object of the invention is to provide gelatine blasting explosives of improved serviceability under conditions of hydrostatic pressure substantially exceeding 10 atmospheres such as may be encountered in submarine blasting or in seismic blasting operations.

A gelatine blasting explosive according to the present invention consists of a liquid explosive nitric ester-nitrocellulose gelatine composition containing at least 35% by weight of a mixture of nitrocellulose and a liquid nitric ester liquid composition based on the weight of said nitric esternitrocellulose elatine composition and 2 /2% to 27 96 by weight of a water insoluble finely divided barium salt of a polybasic acid, the said liquid composition being thickened by the nitrocellulose and containing at least a major quantity of liquid nitric ester.

The said liquid composition may include a liquid nitrobody as for example a mono-nitrotoluol as for instance ortho-nitrotoluol.

The water insoluble barium salt of a polybasic acid is employed in a state of line division passing a- 300 B. S. S. screen and preferably in the form of an impalpa'ole powder such as is used in pigments for paints and enamels, whether produced by chemical precipitation or by milling the naturally occurring mineral. There may be used for instance precipitated barium sulphate, or milled barytes, precipitated barium carbonate, or witherite, or precipitated barium chromate, or barium phosphate.

The improved gelatine explosives may for instance approximate in their compositions to conventional blasting gelatine, sodium nitrate gelignites or ammonium nitrate gelignites. Thus a blasting gelatine-like explosive having very much improved retention of its high velocity of detonation under conditions of increasing hydrostatic pressures may be obtained by incorporating the finely divided water insoluble barium salt of a polybasic acid into ordinary blasting gelatine, preferably during the mixing operation in which the nitroglycerine-nitrocellulose paste is brought into the form of a jelly by effecting complete solution of the nitrocellulose in the liquid explosive nitric ester. In the case of a sodium gelignite-like explosive the finely divided barium salt .i preferably incorporated along with the sodium nitrate or the vegetable tissue ingredients or both into the nitrocellulose-liquid explosive nitric ester paste. In these explosives the proportion of liquid nitric ester-nitrocellulose jelly will usually be at least 50% in order to maintain the power of the explosive. Ammonium nitrate gelignite-like explosives may be prepared in an analogous manner to that employed in the production or" the sodium nitrate gelignite-like explosives. The ammonium nitrate being an explosive salt as well as an oxidising agent, the amount of the liquid explosive nitric ester nitrocellulose jelly may in general be nearer to the lower limit of 35% hereinbefore indicated. As will be understood, however, intermediate types of explosives between these three classes, and other types falling within the definition of the invention but not corresponding closely to the character of blasting gelatine, sodium nitrate or ammonium nitrate gelignites, may also be made. The explosives provided according to the present invention are characterised by the fact that they retain to a remarkable degree the normal velocity of detonation which they exhibit under atmospheric pressure, even when they are subjected to hydrostatic pressures of 20, 30, 40 or even beyond 40 atmospheres; and many of them also maintain their sensitiveness to detonation by the agency of the aluminium encased blasting detonators of customary commercial power unimpaired under these conditions. Moreover their propagating characteristics from cartridge to cartridge as determined by the gap test remain in all cases satisfactory.

Apart from their use in submarine blasting and seismic blasting operations, the improved gelatine blasting explosives may also be employed for other purposes where high velocity of detonation is desired, for example in plaster shooting, or blasting in hard rock, even at ground level.

The invention is illustrated by the following examples in which the parts are parts by weight except Where otherwise indicated.

Example 1 Per cent 80:20 mixture of nitroglycerine and ethylene glycol dinitrate 57.5 Blasting soluble nitrocellulose 2.4 Woodmeal 10.0 Sodium nitrate 24.8 Finely milled barytes as used as a pigment in paints 5.0 Chalk 0.3

The liquid explosive nitric ester mixture, the

nitrocellulose and a portion of the woodmeal are first mixed by hand and the remaining ingredients are introduced one by one into the resulting pasty mass in a McRoberts mixer in the order given, the running of the mixer being continued until the nitrocellulose is completely gelatinised and the other ingredients are well distributed through the resulting jelly. The resulting sodium nitrate gelignite-like explosive is ca'rtridged by extrusion into rigid interconnectable waxed paper containers as used for seismic prospecting.

When a file of cartridges of cm. diameter separated by 1 cm. gaps between their ends is exposed at 40 atmospheres pressure of water for 24 hours it is found that the first cartridge is satisfactorily initiated by a No. 8'aluminium encased lead azide-tetryl detonator and that the third cartridge in the file of cartridges detonates at a velocity of 7500 metres per second.

In a comparative test of an explosive of similar consistency not in accordance with the invention and in which for the barytes there is substituted a further 5.0% of sodium nitrate, the velocity of detonation of the file of cartridges is 1700 at a water pressure of 3.3 atmospheres. At 5 atmospheres the second cartridge fails to detonate.

Example 2 Per cent 80:20 mixture of nitroglycerine and ethylene glycol dinitrate 87.0 Blasting soluble nitrocellulose 7.4

Finely milled barytes as specified in Example l Chalk The liquid explosive nitric ester and the nitrocellulose are first mixed'by hand and the barytes and chalk are then introduced into the resulting pasty mass in a McRoberts mixer the running of which is continued until the nitrocellulose is completely gelatinised and the 'barytes and chalk are well distributed through the jelly. The resulting blasting gelatine-like explosive composition is cartridged by extrusion into rigid containers made of waxed paper. When a file of cartridges of 5 cm. diameter separated by 1 cm. gaps is exposed to a water pressure 0' 3'7 atmospheres for half an hour it is found that the in the file of cartridges detonates with a velocity less than 1500 metres per second under a hydraulic pressure of 20 atmospheres and the velocity of detonation is still -under 1500 metres per second when the hydraulic pressure is as low as '7 atmospheres, whereas the velocity of detonation is 7800 metres per second at atmospheric pressure.

The explosive of Example 2 is suitable for sub- I marine'b'lasting and seismic blasting at hydraulic pressures up to about 4'0 atmospheres and also for normal pressure blasting operations oa'lling jfor high v'elocities'of detonation.

Example 3 Per cent 80 :20 mixture of nitroglycerine and ethylene glycol dinitrate 6520 metres per second.

4 Blasting soluble nitrocellulose 3.2 Woodmeal 7.6 Sodium nitrate 25.8 Milled barytes as used in Example 1 5.0 Chalk 0.3

The explosive is made and cartridged as described in Example 1. When a file of cartridges of 5 cm. diameter separated by 1 cm. gaps is exposed at 40 atmospheres water pressure for half an hour and initiated with a detonator similar to that used in the tests described in the previous examples the third in the file of cartridges detonates at a velocity of 6530 metres per second.

In a comparative test of an explosive of similar consistency not in accordance with the invention and in which for the barytes there is substituted a further 5.0% of sodium nitrate, the velocity of detonation of the file of cartridges is 1710 at a water pressure of 3.3 atmospheres. At 5 atmospheres the second cartridge in the file fails to detonate.

Example 4 The composition is the same as in Example 1 except that precipitated barium sulphate is used instead of milled barytes. The explosive is similarly made and cartrid'ged.

When a similarly arranged file of the cartridges after exposure for 4 hours to a water pressure of 20 atmospheres is similarly initiated the third in the file of cartridges detonates at a velocity of '7900 metres per second.

The manner of making and cartridging the explosive composition is similar to that described in'Example 1.

When a similarly arranged file of the cartridges after exposure for 5 hours at a water pressure of 40 atmospheres is similarly initiated the third in theme of cartridges detonates at a velocity of This barytes modified ammonium nitrate gelignite, unlike conventional ammonium nitrate gelignites, can thus be used for seismic shooting at pressures of the order of 40 atmospheres.

Example 6 Per cent 80:20 mixture of nitrogl-ycerine and ethylene r The explosive is mixed and cartridged in a fashion similar to that of the preceding examples. When-a file of cartridges similarly arrangedand initiated is subjected -to-.a water pressure of atmospheres for 5 hours the third in the file'of cartridges detonates at-a velocity of 7150 metres per second. The explosive 'is suitable for use in seismic blasting.

' barium chromate.

Chalk The explosive composition is made and cartridged in a fashion similar to that described in Example 1. When a file of cartridges similarly arranged and initiated is subjected to a water pressure of 27 atmospheres for 5 hours the third in the file of cartridges detonates at a velocity of 7140 metres per second. This barium chromate modified sodium nitrate is suitable for seismic blasting purposes and submarine blasting purposes.

Example 8 V l The composition is the same as in Example 7 except that finely powdered precipitated barium carbonate is used instead of the barium chromate. The manner in which the explosive is made is otherwise the same as in Example 7 and it is similarly cartridged. When a file of cartridges arranged and initiated in a similar manner is exposed to a water pressure of 27 atmospheres for 5 hours the third in the file of cartridges detonates at a velocity of 6520 metres per second.

Example 9 The composition is the same as in Example 7 except that barium phosphate is used instead of The explosive is similarly made and cartridged.

When a similarly arranged file of the cartridges after exposure for 3 hours to a water pressure of 54 atmospheres is similarly initiated the third in the file of cartridges detonates at a velocity of 7150 metres per second.

Example 10 5 parts of milled barytes as used in Example 1 are worked in a McRoberts mixer into 95 parts of a military gelatine explosive intended to withstand rifle bullet fire without detonating and containing Per cent Nitroglycerine 68.3 Blasting soluble nitrocellulose 5.7 Guncotton 10.0 Mono-nitrotoluol 14.6 Diethyl diphenyl urea 0.9

The explosive is cartridged in the same way as in the preceding examples. When a file f the cartridges arranged and initiated by a similar detonator is exposed at a water pressure of 100 atmospheres for hours the third in the file of cartridges detonates at a velocity of 7500 metres per second.

A similar cartridge of the aforesaid military gelatine explosive composition not in accordance with the invention, due to the absence of barium salt, fails to detonate even at atmospheric pressure when an attempt is made to initiate it with a similar detonator even at atmospheric pressure in the absence of an intermediate primer. When such a primer is used the third in a file of such cartridges detonates at a velocity of 7000 metres per second at atmospheric pressure.

6 Example 11 Per cent :20 mixture of nitroglycerine and ethylene glycol dinitrate 57.5 Blasting soluble nitrocellulose 2.4 Woodmeal 5 De-proteinised de-oiled peanut meal passing 16 and retained by mesh B. S. S. screen 5 Finely milled barytes as specified in Example '1 3 Sodium nitrate 26.4 Di-ammonium hydrogen phosphate 0.3

'The ingredients are mixed and the cartridges are prepared and tested as described in Example 1. on exposure at 27 atmospheres water pressure for 24 hours the third cartridge in the file detonates at a velocity of 6800 metres per second.

Eaample 12 v Per cent 80 :20 mixture of nitroglycerine and ethylene glycol dinitrate 50 Blasting soluble nitrocellulose 2.4

De-proteinised de-oiled peanut meal passing 16 and retained by 100 mesh B. S. S. screen 9 Finely milled barytes as used in Example '1 5 Sodium nitrate 33.3 Chalk 0.3

The composition is mixed and the cartridges are prepared and tested as described in the preceding example except that the time of exposure and the water pressures are different. On exposure for 5 hours to a water pressure of 60 atmospheres the third cartridge in a file detonates at a velocity of 6800 metres per second. On exposing another file for five hours to a water pressure of 106 atmospheres the third cartridge in the file still detonates satisfactorily. At such high pressures however occasional failures occur owing to the detonators being liable to collapse.

The de-proteinised de-oiled' peanut meal which is used in Examples 11 and 12 is the dried substantially de-proteinised material obtained by aqueous alkaline extraction, washing and dewateringof peanuts from which the oil has been removed successively by expression and by extraction with a volatile oil solvent. The screened material has a 'bulk density of approximately 0.46 gm. per 0. 0. under a packing pressure of 25 lb./sq. in. and approximately 0.51 gm. per 0. c.

under a packing pressure of 75. lb. /sq. in. It

gen and 6% hydrogen.

Example 13 v Per cent 80:20 mixture of nitroglycerine and ethylene glycoldinitrate 50 Blasting soluble nitrocellulose 1.8 Oat husk meal 9 Barytes as used in Example 1 5 Balsa woodmeal 3.2 Sodium nitrate 30.7 Chalk 0.3

The composition is mixed and the cartridges are made up and tested as in the preceding examples, except that the gaps between the cartridges are increased to 2.5 cm. and a No. 6 detonator is used instead of a No. 8 When exposed for 24 hours to a water pressure of 66 atmospheres the velocity of detonation of the third cartridge in the file is 6250 metres per second.

agsrv cos 7 Example 14 Per cent 80:20 mixture of nitroglycerine .and .ethylene glycol dinitrate 45 Blasting soluble nitrocellulose 3.5 Barytes as used in Example 1 5 Ammonium nitrate 145.9 Chalk D3 Di-ammonium hydrogen phosphate... 0.3

The ingredients are mixed and the cartridges are made up and tested as in Example :12 meant that the gaps between the cartridges are again reduced to 1 cm. When subjected 01224 incurs to a water pressure of atmospheres the velocity of detonation is 6820 metres per second. In a test where the water pressure is increased to 66 atmospheres the cartridge detonates satisfactorily.

The composition is mixed and the cartridges are made up and tested with a No. ,6 detonator as in Example 13 except that the gaps between the cartridges are 0.5 cm. When subjected for 24 hours to a water pressure of atmospheres the velocity of detonation is 6500 metrespers'ec- 0nd.

Example 16 Per cent :20 mixture of nitroglycerine and ethylene glycol dinitrate 31.5 Blasting soluble nitrocellulose--- 2.1 Mono-nitrotoluol 1.7 Woodmeal 0.2 Ammonium nitrate 38.5 'Di-ammonium hydrogen phosphate 0L5 Chalk 0.3 Barytes as used in Example 1 25.2

The composition is mixed 'and'the cartridges are made'up and tested .as in Example 14. when subjected for '24 hours to awater pressure of 50 atmospheres the velocity of detonation is 6250 @metres per second.

ln'the preceding examples the :term blasting soluble nitrocellulose means the product .of mitration of purified .cotton cops by the pot process to a nitrogen content 0:11.95 to 12.25%. The product is at least soluble in an ether-alcohol solution and has a "viscosity 01 to .300 c. g. s. in solution of 3 gms. in 100ml. acetone 95% at 20 C.

What we claim is:

1. YA gelatine blasting explosive containing 8 2 /2% to 2'7 /2% by weight of a water insoluble finely divided barium salt of a polybasic acid, and at least 35% by weight of a liquid composition consisting of at least a major quantity of liquid nitric ester thickened by a minor quantity of nitrocellulose.

2. A ge'latine blasting explosive containing 2 /2% to 27. 5% by weight of a water insoluble finely divided barium salt of a polybasic acid, at least 35% .by weight of a liquid composition consisting of .at least a major quantity of liquid nitric ester thickened by a minor quantity of nitrocellulose, and a liquid nitrobody.

3. A gelatine blasting explosive .as claimed in claim '2 wherein the liquid nitrobody is .a mononitrotoluol.

4. A gelatine blasting explosive as claimed in claim 2 wherein the liquid nitrobody is orthb- .nitroto'luol.

5. A. gelatine blasting explosive as claimed in claim 1 wherein the water insoluble barium salt of a polybasic acid is barium sulphate.

6. A gelatine blasting explosive as claimed in claim 1 wherein the water insoluble barium sulphate of a polybasic acid 'is milled barytes.

'7. A gelatine blasting explosive as claimed in claim 1 wherein the water insoluble barium salt of a polybasic acid is precipitated barium car- 'bonate.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,964,755 Woodbury July 3, 1934 2,362,618 "Winning Nov. 14, 1944 FOREIGN PATENTS Number Country Date 6,289 Great Britain 1895 28,710 Great Britain 1903 15,564 Great Britain 1905 579,376 Great Britain Aug. 1, 1946 OTHER, REFERENCES Davis, The Chemistry of Powder and Explosives, pub. (1943) by John Wiley & Sons, New York, Chapman & Hall Ltd., London, page 334. (Copy in Scientific Library.) 

1. A GELATINE BLASTING EXPLOSIVE CONTAINING 21/2% TO 271/2% BY WEIGHT OF A WATER INSOLUBLE FINELY DIVIDED BARIUM SALT OF A POLYBASIC ACID, AND AT LEAST 35% BY WEIGHT OF A LIQUID COMPOSITION CONSISTING OF AT LEAST A MAJOR QUANTITY OF LIQUID NITRIC ESTER THICKENED BY A MINOR QUANTITY OF NITROCELLULOSE. 